Conventionally, magnetic tape recorders such as video tape recorders are designed to drive a tape in the forward and reverse directions by using exclusively a supply reel driving turntable and a take-up reel driving turntable, respectively.
A tape running direction is selected by selectively engaging an idler gear to either the supply reel driving turntable or the take-up reel driving turntable. The idler gear is supported on an idler arm which is rockably coupled to a capstan drive mechanism. The capstan drive mechanism has a capstan motor for rotating a capstan in one direction or the other direction. Thus, the idler arm is rocked toward the supply reel driving turntable or the take-up reel driving turntable, in response to a rotating direction of the capstan motor.
When an operation mode of the video tape recorder changes from a forward reproducing operation to a reverse reproducing operation or vice versa, a tape is typically held by the capstan and a pinch roller for pressing the tape to the capstan. Thus, the tape is driven in the reverse direction simultaneously to the change of the operation mode between the forward reproducing operation and the reverse reproducing operation.
On the other hand, the take-up reel driving turntable or the FRD turntable is driven with a delay of time from the mode change because the idler gear takes time during its swing from the take-up reel driving turntable to the supply reel driving turntable.
Thus, the video tape recorder fails to drive the tape immediately at the mode change. As a result, a loose tape tension occurs on the tape for the delay time, causing troubles on reproduced signals such as reproduced images and sounds.
In order to solve the troubles, in the conventional video tape recorder an additional motor for exclusively driving the reel driving turntables are provided for maintaining a desired tape tension at the mode change. Therefore, such a conventional video tape recorder has a problem of cost due to the additional motor.